Clinical Cases, Chairside and Labside

Lithium disilicate veneers

This 36-year-old female patient wanted to replace her bonded composite veneers. She expressed the demand for a brighter smile with a bleached color (NW 0.5) selected for her six maxillary anterior teeth and first premolars. However, she wanted the tooth preparation for this treatment to be as minimally invasive as possible.

In addition, she specifically requested that the teeth be square in form, with the lateral incisors the same length as the central incisors and the incisal edges straight, without rounded corners – clearly influenced by modern aesthetic standards. We explained our concerns regarding potential aesthetic and functional issues that might necessitate further intervention or adjustments, but she remained firm in her choices.

FROM DESIGN TO PRESSED FRAMEWORK

In line with the patient’s demands, it was planned to restore her maxillary teeth from first premolar to first premolar with lithium disilicate veneers (Amber® Press HT in the shade W2), which would allow for the desired minimally invasive preparations and bright appearance. Following tooth preparation, an analog impression was taken and sent to our laboratory. After the production of the model, the case was digitalized for the virtual designing of the veneers. In order to create space for the porcelain, the labial surfaces of the full-contour restorations were reduced by 0.3 mm with the software (exocad® DentalCAD, Figs. 1 and 2).

The frameworks were then milled in wax and pressed in Amber® Press HT W2 (Figs. 3 and 4). Sprues were cut and the surfaces of the veneer frameworks processed with a Diagen-Turbo-Grinder Ø 3,5 x 11 mm Cone and Wheel.

We explained our concerns regarding potential aesthetic and functional issues that might necessitate further intervention or adjustments, but the patient remained firm in her choices.

Fig. 1. Screenshot revealing the prepared tooth structure underneath transparent full-contour veneers.

Fig. 2. Cutback design of the eight veneers.

Fig. 3. Milled wax frameworks produced for the pressing procedure.

Fig. 4. Lithium disilicate framework on the master cast.

Fig. 5. Chroma map for micro-layering and internal staining on lithium disilicate.

MICRO-LAYERING AND INTERNAL STAINING

A chroma map was developed to plan the layering procedure (Fig. 5). When applying CERABIEN™ MiLai to lithium disilicate, it is essential to conduct a wash bake with Value Liner (Figs. 6 and 7). Apart from securing a strong bond to the ceramic, Value Liner adds opacity to the highly translucent lithium disilicate framework and controls the decrease in brightness. This is necessary to avoid a greyish appearance of the restorations, which is otherwise activated by the application of the porcelains. What followed was the internal staining procedure - applied as a color foundation and for characterization of mamelon structure according to the appearance on the patient’s mandibular incisors (Fig. 7). In our obligation to mimic nature, the enhancing of the restorations’ depth and chroma with internal stains appears to be the best approach for providing beautiful results. Figures 9 to 13 illustrate the micro-layering procedure carried out using the one-bake technique.

Fig. 6. Veneer treated with CERABIEN™ MiLai Value Liner 1.

Fig. 7. Restorations after the wash bake (770 °C, hold time 00:45 min.).

Fig. 8. Results after internal staining and firing at 740 °C, no holding time, with vacuum.

Fig. 9. Application of CERABIEN™ MiLai LT1.

Fig. 10. Layering with Creamy Enamel mixed with ELT1 in the ratio 70 to 30 percent …

Fig. 11. … followed by ELT1.

Fig. 12. Structuring of the incisal third. Mesial and distal with a mixture of LTx and ROYAL BLUE (ratio 70 to 30 percent); pure LTx and LT1 in the middle; completing the shape by creating the HALO effect with CREAMY ENAMEL.

Fig. 13. The veneers after the bake at 760 °C for 00:45 mins.: the effectiveness is immediately visible.

FINISHING AND POLISHING THE PORCELAIN SURFACE

Personal experience shows that it is beneficial to use only a few selected standard instruments for daily work. This way, routines are established and predictable outcomes are supported. To plan the surface texturing procedure, the desired morphological and texture details were marked on the surface of the veneers with a bi-color pencil (Fig. 14). For contouring, we used different diamond instruments and the Carving Diamond Point set developed by Yasuhiro Odanaka (Ceraconcepts) to add special morphological and surface features. Mechanical polishing was then accomplished with cone sandpapers and special silicon rubbers (SoftCut-E PA / PB shape unmounted wheels, Shofu Dental, Fig. 15). In the final step, it is essential to use pumice to remove the silicone residues from the surface. If this step is skipped, the subsequently applied glaze may not connect well with the surface. Consequently, a remake of the glazing step, especially on lithium disilicate surfaces, may be necessary. After glazing, the fit was checked again and the polishing process was completed by using a diamond polishing paste (Amber Glow, HASS in this case).

Figures 16 to 18 show the final veneers after the application of CERABIEN™ ZR FC Paste Stains and Glaze and a glaze firing at 730 °C (holding time 00:45 mins.) under different light conditions and from different views, revealing the natural color, translucency and surface texture appearance of the restorations. Note that not only the mechanical treatment, but also the temperature and holding time during the final bake have an impact on the surface texture and roughness.

Fig. 14. Veneers with highlighted surface details.

Fig. 15. Surface structure integrated with selected instruments.

Fig. 16. Final restorations on the model: Frontal view displaying the square shape of the restorations and the desired length.

Fig. 17. Final restorations on the model: Labial view of the first quadrant.

Fig. 18. Final restorations on the model: Labial view of the second quadrant.

DEFINITIVE PLACEMENT AND TREATMENT OUTCOME

After a successful try-in, it was time for the definitive placement of the veneers. In this context, the correct material-specific pre-treatment of the bonding surfaces and adherence to appropriate bonding protocols has a decisive impact on long-term success of the restorations. The veneers’ bonding surfaces were treated with hydrofluoric acid as recommended, and the restorations were adhesively cemented with PANAVIA™ V5 (Kuraray Noritake Dental Inc.). The system features matching try-in pastes that allowed an assessment of the final shade beforehand. By choosing the right shade of cement paste, it is possible to fine-tune the chroma and translucency of a restoration. The treatment outcome is shown in Figures 19 to 21.

FINAL SITUATION

Fig. 19. Adhesively cemented veneers …

Fig. 20. … in the patient’s mouth.

Fig. 21. View of the maxillary teeth with restorations that fulfil the demands of the patient while still providing a natural look and proper function.

Dental technician:

LEONIDAS DIMITRIOU

Born in Athens, Leonidas Dimitriou graduated as a dental technician in 1986 and continued his studies at the Department of Dental Technology at the Technological Educational Institution of Athens. Over the years, he has attended numerous leading dental seminars and, since 1993, has been the owner of the DENTECH dental laboratory. In 2015, he also became a laboratory co-operator at the Department of Dental Technology, Technological Educational Institute of Athens.

Passionate about education and knowledge transfer, Leonidas has been an official Noritake instructor and speaker since 2017. In 2018, he began teaching ceramics and fixed prosthodontics at the University of West Attica, Department of Dental Technology. More recently, he has organized courses on Noritake ceramic materials and lectures regularly at international conferences and seminars.